Why Dae Isn't Worried
Hysteria's Getting Attacked
The Org Shacking In Fear
Galatea Sensing it in the Bath
It was pretty well explained in the chapter where the Claymores beat the AE what happened. AE need experience to become stronger at fighting a target. It took years for the ones that killed Isley to get to the point that they could do that. The ones sent after Riful weren't meant to kill her, just track her for Alicia and Beth. They did as well as they did because the caught her by surprise, and because Riful had Beth and the Destroyers spikes to deal with. Also their were 11 AE per AO, a situation where the AE could escape, and have new ones made. This time their was no where for the AE to retreat to, and with multiple foes, with many different styles, they couldn't adapt in time.
imo Dae meant that cassandra was first one to awaken, when he said "first one of them". I think his true plan was to create a new AO's, since he believes that Alicia and Beth were not a success experiment . REally hope to see Awakened cassandra new chapter